3

I/O Pins Configuration Table

Pin

Symbol

Description

I/O Type

Function

1

LED A

LED Anode

Input

2

LED C

LED Cathode

Output

Leave this pin unconnected.

3

TXD

Transmit Data

Input,

This pin is used to transmit serial data when SD/Mode pin is low. If this

Active High

pin is held high longer than ~100

µs, the LED would be turned off when

used in conjunction with the SD/Mode pin. TXD is low at initialization.

4

RXD

Receive Data

Output,

This pin is capable of driving a standard CMOS or TTL load. No external

Active Low

pull-up or pull-down resistor is required. It is in tri-state mode when the

transceiver is in shutdown mode and during digital serial programming

operations. RXD is high at initialization.

5

SD/Mode Shutdown/

Input,

The transceiver is in shutdown mode if this pin is high for more than

Mode Select

Active High

400

µs. On the falling edge of this signal, the state of the TXD pin sampled

and used to set receiver low bandwidth (TXD=low) or high bandwidth

(TXD=high) mode. See Figure 2 for bandwidth selection timings. SD is low

at initialization.

Supply

Supply

Regulated, 2.7 to 5.25 Volts.

Voltage

Voltage

7

NC

No Connect

No Connect

8

GND

Ground

Ground

Connect to system ground.

–

Shield

EMI Shield

EMI Shield

Connect to system ground via a low inductance trace. For best

performance, do not connect directly to the transceiver pin GND.

Recommended Application Circuit Components

Component

Recommended Value

Notes

R1

0

Ω ± 5%, 0.5 Watt, for 2.7 V

1.8

Ω ± 5%, 0.5 Watt, for 3.0 V

4.7

Ω ± 5%, 0.5 Watt, for 3.3 V

6.8

Ω ± 5%, 0.5 Watt, for 3.5 V

CX1

0.47

µF ± 20%, X7R Ceramic

1

CX2

6.8

µF ± 20%, Tantalum

2

Notes:

1. CX1 must be placed within 0.7 cm of the HSDL-3603 to obtain optimum noise immunity.

2. In environments with noisy power supplies, supply rejection performance can be enhanced

by including CX2, as shown in Figure 1: ”HSDL-3603 Functional Block Diagram“ on Page 2.